Offline stream thumbnails

How would I go about getting an offline thumbnail/avatar set for my stream? Or is is supposed to automatically be pulled from the avatar set on the streaming service itself?
 
https://derpibooru.org/channels/804 under “Artist Simulator 2017” has the default one, even though I’ve got an avatar set both here and on Picarto.

@evan555alpha  
Picarto’s API is supposed to give us this information, but… well let’s just say the API is not good. We’re looking into a way to just grab the image the old fashioned way.

@The Smiling Pony  
So it can’t be set manually, then?

@evan555alpha  
Not at present, no.